Diagnostic precision of sentinel lymph node biopsy in penile cancer

INTRODUCTION: Sentinel lymph node biopsy (SLNB) was designed as a minimally invasive method for evaluation of nodal involvement in patients with penile cancer and nonpalpable lymph nodes. Nevertheless, SLNB is not used in a regular basis due to the lack of studies that adequately characterize the performance of this procedure. The purpose of this study was to evaluate the diagnostic performance of SLNB in patients with infiltrative penile carcinoma without palpable inguinal lymph nodes in a Colombian population. MATERIALS AND METHODS: This is a retrospective observational study of 89 patients diagnosed with infiltrative penile squamous cell carcinoma with nonpalpable inguinal lymph nodes. These patients underwent partial or complete penectomy, along with SLNB, between 2008 and 2017. Those individuals with a positive SLNB underwent inguinal lymphadenectomy, while those with a negative SLNB were followed on a quarterly basis with a physical examination and imaging to assess relapse. Statistical analysis was done using the STATA 14 software. A contingency table was made to calculate sensitivity, specificity, positive predictive value, negative predictive value, and exactitude, each one with its own confidence interval (CI) of 95%. RESULTS: There was an average follow-up of 31.4 months, and all 89 patients were evaluated; most primary tumors were T2 (55%), followed by T1 (37%), all of which were subclassified as T1b and T3 (8%). Tumours were most frequently located in the glans (43%). All patients were classified as cN0 and underwent SLNB. Sixty-one patients (69%) tested negative in the SLNB, four of whom (6%) presented with lymph node relapse. On the other hand, 28 patients (31%) tested positive in the SLNB and consequently underwent inguinal lymphadenectomy, seven of whom had negative lymph nodeinvolvement (25% false positives). According to the results, the sensitivity was 84% (95% CI, 65.3–93.6) and the specificity was 89% (95% CI, 79.4–94.7), with a false-negative rate of 6.5%. CONCLUSIONS: The SLNB using radiotracer can be a useful method for lymph node staging in patients with penile cancer and nonpalpable lymph nodes when performed in experienced centers.